Reference:

• According to a study conducted by scientists at the Institute of Nano Science and Technology (INST), Mohali, nanoplastics released from single-use PET bottles damage gut bacteria and human cells.

Key Points:

• Team: The study was led by Prof. Manish Singh, Prashant Sharma, and Sakshi Dagaria from the Chemical Biology Unit of INST.
• Objective: To understand the biological impacts of nanoplastics (PBNPs) released from single-use PET bottles, particularly on the gut microbiome, blood cells, and general cellular responses.

Process:

• INST prepared nanoplastics (50–850 nanometers) from PET bottles in the laboratory to replicate real environmental conditions.
• These nanoplastics were tested on three biological models:
• Lactobacillus rhamnosus: A beneficial gut probiotic bacterium.
• Red Blood Cells: To assess blood compatibility.
• A549 Human Epithelial Cells: A model for general cellular responses.

Impact on Gut Bacteria (Gut Microbiome)

Effects on Lactobacillus rhamnosus:

• Reduced Growth: Exposure for 16 days caused dose- and time-dependent reductions in bacterial viability and proliferation.
• Membrane Damage: Confocal microscopy confirmed damage to bacterial membranes.
• Decline in Protective Functions: Antioxidant and antibacterial activities decreased, affecting the bacterium’s ability to protect the gut.
• Biofilm & Autoaggregation: Nanoplastics increased biofilm formation and autoaggregation, indicating dysbiosis.
• Antibiotic Sensitivity: Increased sensitivity to antibiotics, complicating antibiotic resistance (AR) dynamics.
• Reduced Colonization: Adhesion to colon epithelial cells decreased, reducing colonization capability.

Spread of Antibiotic Resistance (AR):

• Nanoplastics promote AR gene transfer through two mechanisms:
• Direct Transformation: PBNPs transport AR plasmids across bacterial membranes, enabling gene transfer from E. coli to L. acidophilus.
• OMV-Induced Transfer: Nanoplastics trigger oxidative stress and membrane damage, activating stress genes and increasing secretion of outer membrane vesicles (OMVs).
• These OMVs carry AR genes and transfer them to unrelated bacteria.
• This mechanism may turn beneficial bacteria into reservoirs of AR genes, which may later transfer to pathogenic bacteria, intensifying the global AR crisis.

Impact on Human Cells

Red Blood Cells:

• At high concentrations, nanoplastics caused membrane damage and hemolytic changes (premature cell destruction).
• This may affect oxygen-carrying capacity and overall blood stability, potentially leading to anemia-like conditions.

A549 Epithelial Cells:

Short-term exposure:

• Minimal effects observed.
• Long-term exposure:
• DNA Damage: Genotoxic effects leading to DNA damage (γH2AX marker).
• Oxidative Stress: Increased reactive oxygen species (ROS), causing cellular damage.
• Apoptosis: Increased markers of programmed cell death.
• Inflammation: Enhanced pro-inflammatory signaling (IL-6, TNF-α), potentially causing chronic inflammation.
• Metabolic Changes: Alterations in glucose metabolism, amino acid balance, and lipid pathways affecting energy and nutrient metabolism.
• Mutagenic Potential: No direct mutagenicity in Ames test, but mutagenic potential increased after metabolic activation, indicating bioactivation-dependent genotoxicity.

Characteristics and Risks of Nanoplastics:

•  
• Size & Bioavailability: PBNPs (50–850 nm) are small enough to penetrate cell membranes, gut walls, and tissues. They may be 1000 times more toxic than microplastics.
• Trojan Horse Effect: Nanoplastics carry harmful chemicals (phthalates, bisphenols, heavy metals), increasing toxicity.
• Environmental Relevance: INST generated nanoplastics from real PET bottles, replicating environmental pollutants more accurately.
• PET bottles release nanoplastics through sunlight exposure, heat, and mechanical stress.
• Antibiotic Resistance Risk: Nanoplastics promote AR gene spread, worsening global health challenges.

Plastics

• Plastics are a broad category of synthetic or semi-synthetic organic compounds used to make various products.
• The word “plastic” comes from the Greek word plastikos, meaning “capable of being molded.”

Classification of Plastics

Based on Structure:

Thermoplastics:

• Soften on heating and harden on cooling; the process is reversible.
• Ideal for recycling.
• Examples: Polyethylene (PE), Polypropylene (PP), Polyvinyl Chloride (PVC), Polystyrene (PS), PET.

Thermosetting Plastics:

• Become permanently hard upon heating; cannot be softened again.
• Difficult to recycle.
• Examples: Bakelite, Melamine, Epoxy resins.

Types of Plastics and Recycling Codes (Resin Identification Codes):

These codes help identify plastics based on their chemical composition for recycling purposes.